DuCTT is a lightweight robot that can navigate, inspect, repair and maybe one day clean air duct systems.
With nearly 90 percent of our days spent indoors, wouldn’t you like to know that you’re not breathing a ridiculous amount of pollutants and debris? Truth be told, air conditioning and heating systems tend to be lead contributors to many air quality problems, often experienced by those working in buildings. The problem is that these ceiling ducts are often confined and otherwise inaccessible for inspection and repair, especially in the event of emergencies. And while there are unmanned, remote-controlled devices that can attempt to clean them with brushes, these gadgets are unable to access the remote parts of the HVAC units.
In an effort to solve this problem, researchers in the UCSD Robotics Lab have developed a duct-exploring robot based on the principles of tensegrity — a design paradigm which combines components under pure tension and compression to make mass efficient, accurately controllable structures.
What sets tensegrity robots apart is their characteristic lightweight and flexibility. DucTT consists of two linked tetrahedral structures, each containing a linear actuator, connected by a system of eight space-age cables similar to the tensioned frame of a pop-up tent. Inspired by a human’s own shoulder joints, a series of aluminum tubes and cables provide an extensive range of motion with a small number of actuators. Meanwhile, the batteries, electronics, motors and sensors are all embedded within these tubes to shield them from the gas or liquid that may be flowing within the duct during an inspection.
No different than an inchworm, DucTT makes its way through ducts in any orientation and can even accurately negotiating the intersection of two or more air pipes in deliberate fashion. The robot moves by first anchoring its top half, pulling its bottom half upward, and then anchoring its bottom half while the upper half extends again.
In terms of DucTT’s electronics, its paper reveals that a BeagleBone Black is tasked with handling high level control, while three Arduinos are used to perform position control of the six cable actuators. A single I2C bus enables communication between all the microcontrollers with the BeagleBone set as master. The robot is currently powered by eight 18650 lithium-ion cells, and since much of its bars are devoted to the batteries themselves, it can run for up to six hours continuously, untethered, on a single charge.
“Power and communication are fed between the tetrahedra through a single ribbon cable. Quadrature encoders are used to read motor position and conductive rubber cord stretch sensors are placed in parallel with the linear actuators to get rough length estimates. The Arduino also monitors the current being fed into the linear actuator to determine when adequate force has been exerted on the duct walls,” the team writes.
That all being said, DucTT isn’t equipped with any actual duct-cleaning gear at the moment, but it would presumably be easy to throw on some rotating brushes or a compressor of some sort. You can read all about the project here, or watch it in action below!